Figure 1. Association between pregnancy outcome and female age, treatment cycles, duration of Gn used and transferable embryos in "unexpected" group. A threshold, nonlinear association between pregnancy outcome and these independent predictive factors was found (P<0.05) in a generalized additive model (GAM). Solid rad line represents the smooth curve fit between variables. Blue bands represent the 95% of confidence interval from the fit. Pregnancy outcome was defined as live birth rate; Gn.